Safety guard for centrifugal machines



April 24. 1928.

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April 24, 1928. 1,667,416

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April 24, 1928. 1,667,416

c. H. GARLAND SAFETY GUARD FOR CENTRIFUGAL MACHINES Filed Marbh $1. 1926 5 Sheets-Sheet 4 WMW.

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April 24, 1928.

C. H. GARLAND SAFETY GUARD FOR GENTRIFUGAL MACHINES Filed March 31. 1926 5 Sheets-Sheet 5 Patented Apr. 2 4, 1928.

UNITED STATES PATENT OFFICE.

CLARENCE H. GARLAND, OF BOSTON, MASSACHUSETTS, ASSIGNOR TO AMERICAN TOOL AND MACHINE COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OF MAS- SACI-I'USETTS.

SAFETY GUARD FOR CENTRIFUGAL MACHINES.

Application filed March 31, 1926. Serial No. 98,788.

This invention relates to protecting devices for centrifugal machines or centrifuges as they are commonly known; and more particularly to a cover for the casing housing the centrifugal element thereof.

Centrifugal machines are now widely used in the sugar industry for drying out the damp crystals of sugarcoming from the evaporating pans, and are also much used in laundries for removing the greater portion of the water in drying clothes. They consist essentially of a perforated basket into which the material to be dried is placed and a housing surrounding the basket. This basket is rotated at a high speed, generally by an electric motor, and the liquid is forced out through the perforations in the side of the basket by centrifugal force.

When the *material is substantially dry the device is stopped and the attendant then removes the contents, either through the top or through a trap door in the bottom. In either case the top of the casing is normally open and it is always possible for the attendant to reach in either with his hand or arm or with some implement after the device has been started or before it has stopped. This is a very dangerous practice and to prevent it as well as to' prevent mishaps occurring from the accidental dropping of objects into the basket during the operation of the device, various States have passed laws compelling the use of some safety device in connection with these machines. This invention furnishes a safety device of this kind which will accomplish the desired result of providing for the safety of the operator thus complying with the statutes in this regard.

The improved device comprises a movable cover adapted to enclose the top of the easing when the machine is in operation and to prevent anything from falling or being inserted into the basket; and means'comprising interlocking elements so devised that the cover can not be opened until the rotating element is completely stopped. As these machines are generally operated by comparatively unskilled labor, it is essential that the safety device be certain in operation and fool-proof in use.

To this end there are provided two interlocking devices which combined positively accomplish the desired result. The first is that the motor switch is arranged to be operated by the cover operating lever so that the switch can only be closed when the cover is in a closed position. The second is that a part is provided on the motor shaft which interlocks with a non-rotating part connected to the cover operating lever so that the cover can only be opened as the motor has stopped. This connection is constructed in such a way that it is impossible to start the motor when the cover is open..

A further feature of the device is a means for holding the cover in open position.

Further advantages of this invention will be obvious from the detailed description and the claims appended thereto.

In the drawings:

Fig. 1 is an elevation of the device showing the pulley casing in section better to illustrate the construction of the device and showing the cover in closed position;

Fig. 2 is a similar view to Fig. 1 showing the cover in open position;

Fig. 3 is a plan view of the device with the cover closed and the pulley casing removed;

Fig. 4: is a fragmentary plan view of the actuating member and switch mechanism;

Fig. 5 is a section on the line 5--5 of Fig. 4;

Fig. 6 is an elevation taken approximately on the line 66 of Fig. 4 and showing the operating lever in section;

Fig. 7 is an elevation of the end of the motor shaft and lever engaging mechanism showing the pulley casing in section; and

Fig. 8 is a section on the line 8,8 of Fig. 7.

The device consists essentially of a casing 1 which houses the rotating basket element adapted to contain the material to be dried.

The rotating element is driven by means of a belt 2 engaging a pulley 3 on the shaft 4 of a motor 5. This motor is mounted on a suitable base 6 attached to the casing 1. A cover 7 is fixed to a shaft 9 which turns in bearings in lu s 8 on the casing l. The cover may be opened and closed by rotation of the shaft 9, and preferably a counterweight/10 is fixed to this shaft so that the cover is easily movable.

A bell crank lever 11 is fixed to one end of the shaft 9, and comprises an arm 12 which is connected to one arm 13 of a second bell crank lever fulcrumed at 18, by means of a link 14 of adjustable length. The link 14 has right and left hand screw threads at its opposite ends as shown at 15 and nuts 16 are provided for locking the link in an ad usted position. The other arm 13 o the last named bell-crank lever has a handle lever 17 hinged to its free end. This handle lever 17 is hinged to lever 13 in such a manner as to be capable of independent horizontal swinging motion but is substantially rlgid with lever arm 13 as respects movementin a vertical plane. Lever 17 is provided with a handle 19 at its front or forward end. This handle lever 17 is constrained to move in a predetermined path by the U-shaped guides 21 and 22. This provides for a movement starting with the position shown in Fig. 6 first in a horizontal plane between portions 23 and 24 of the guides, then in a vertical plane between portions 25 and 26 of the guides, and then in a horizontal plane be tween portions 27 and 28 of the guides 21 and 22. Guide members 21 and 22 are fastended to the casing 1 in any suitable manner as for example by bolts 29.

A switch box 30 is fixed to the casing 1 and provided with a cable duct 31 through which the conductors are lead from a suitable source of electric energy to the switch box and thence to the motor 5. The electric connections to the motor are not shown as they form no part of the present invention and are assumed to be of any conventional form. The switch box is shown in detail in Fig. 5 and comprises a casing 32 forming a backing and sides of the box and a cover 33 having an aperture 34 therein for a purpose to be later described. The casing 32 is fastened to the centrifugal casing 1 1n any suitable manner. An insulating block 35 is fitted in the bottom of the casing 32 and forms a mountin for the resilient contact elements 36 and 37 of the switch. (These elements 36 and 37 are fastened to the block 35 in any suitable manner through. the strips 38 and 39 respectively.) Binding posts are mounted on the strips 38 and 39, one of WlllCll is shown at 40 in Fig. 5. The other post is mounted on strip 39 but can not be seen in the section as taken.

The switch arm 17 carries an insulating block 41 which is attached to the arm by suitable means as for example a screw 42. This block 41 has a metal contact member 43 surrounding the end thereof and adapted to fit between contact elements 36 and 37. Thus when the handle 17 is moved in the direction of the arrow 20 in Fig. 4 the contact element 43 is withdrawn from between elements 36 and 37 through the aperture 34 in the cover 33 and as this contact element 43 is now disconnected from both the motor and the line, there is no danger of shock to the operator.

The bell crank lever 11 is provided with a second arm 44 substantially opposite the arm 12, and the arm 44 is connected to the vided with a yoke portion 50 (Fig. 7). The

yoke 50 is pivoted at 51 to suitable lugs on a collar member 52 surrounding an extended sleeve or hub portion 53 of the pulley 3. (This sleeve portion 53 may have one or more lugs or peripherally spaced teeth 55 thereon.) The collar member 52 has inwardly directed teeth 56 adapted to mesh with the teeth 55 as the collar 52 is swung from the full line position toward the dotted line position as seen in Fig. 8. The pulley and adjacent parts are surrounded by a housing 57 to protect them from injury.

The operation of the device is as follows:

Starting with the cover 7 in a closed position as shown in Fig. 1 and with the lever in the position seen in Figs. 4, 5 and 6 so that the switch is closed and the motor in operation, the first movement in stopping the device is to swing the handle 19 in the direction of the arrow, 20, Fig. 4. This disengages the contact element 43 from between parts 36 and 37 and thereby opens the motor circuit. The basket will then gradually slow down and stop. After the basket is stopped, the lever 17 can be moved vertically between guide portions 25 and 26 of the guides 21 and 22 respectively, which will swing the bell crank lever 13 about its pivot 18 and thereby rotate the shaft 9 and open the cover. This action will also move the link 46 to the right, rotating the shaft 47 in a clockwise direction as seen in Fig. 1 and bringing the collar 52 into the dotted line position as seen in Fig. 8, (wherein the teeth 56 engage and pass beyond the teeth 55 of pulley 3). The lever 17 is then swung to the left, that is in a direction opposite to the arrow 20 in Fig. 4, and between portions 27 and 28 of the guides 21and 22. (This action locks the cover in open position but allows the basket to be revolved by hand while loading the machine.) As the pulley is connected to the rotating element of the device through belt 2, the device will be locked before the operator can raise the cover 7 sufficiently to insert his arm or anything else into the device. Special attention is called to the feature of the locking device being rendered inoperative in the full open position of the cover. Since the basket must be fully stopped be fore the cover can be opened, and since the motor can not be started unless the cover is fully closed, this does not detract from the safety features of the device or make it any stantially fool-proof.

Ido not wish to be limited to the exact" form of the device shown and described herein but merely by the scope of the appended claims.

I'claim: 1. A centrifugal machine of the type having a rotating basket, a casing therefor, a movable cover for the casing, and means for driving the basket, said machine comprising common means for movin the cover and for starting and stopping the asket, said means being so 'constructed and arranged'that the cover cannot be moved from closed to open position as long as the basket is turning.

2. A centrifugal machine of the type having a rotary basket,.means for drivmg the basket, a casing for the basket, and a movable cover for the casing, said machine comprising a handle for opening the cover, and means actuable by the'handle during the first part of its movement for stopping the basket driving means.

3. Protecting means for a centrifugal machine of that type having a rotar basket, an electric motor for driving the asket, a casing for the basket, and a movable cover for the casing, said protecting means comprising a handle for moving the cover, and a switch element actuable by the handle t the motor, and ineans for opening the switch and the cover, .said means being so constructed and arranged as to open the switch prior to opening the cover. 7 g

8. In a protecting device for an electrically driven centrifugal machine, a cover for the machine, a driving moto'r, and manually operable means for opening the cover, said means locking the cover in closed position whenthe motor is in operation.

9. In a protecting device for an electrically driven centrifugal machine, a cover for I v the machine, a drivin motor, a switch therefor, manually opera le means for opening theswitchand thereafter opening the cover, and means for locking said manually operable means whereby to retain the cover closed as long as the centrifugal element is in motion in response to energy from said motor.

10. In a protecting device for an electrically driven centrifugal machine, a cover for the machine, a driving motor, a controlling switch therefor, and lever means, including an element of said switch, for moving the cover so arranged that the switch must be opened before the lever can be employed to raise the cover, said lever means also having a part which cannot be moved to the osition to open the cover when the centri ugal element is in motion in response to energ from said motor.

11. In a protecting device for a centrifugal machine having a rotary basket, a cover for the machine, a basket driving shaft, a lug movin .with the shaft, and means to open and c ose said cover, said means com-* prising a non-rotary part engageable with break the motor circuit during the initia said lug when the cover is in partly open part of the movement of the handle in opening the cover.

4. A protecting device for centrifugal machines, comprising a cover member for the machine, and means to open and close said cover so constructed and arranged that the cover is closed whenever the drlving connections for the machine are inwoperative position. 2

5. In a protecting device for a centrifu al machine of the type having a rotating e ement and means for driving said element, a cover member adapted to overlie the top of the machine, and manually operable means adapted first to stop said rotating element and then to open the cover.

6. In a protecting device for centrifugal machines, a cover'member adapted to overlie the top of the machine, manually operable means to open and close the cover, and means preventing operative movement of said cover opening and closing means as long as the rotary element .of the machine is "ppsition and not engageable with said lug in ll opeln position.

12. a protecting device for a centrifugal machine having a rotary basket, a cover or the machine, an electric motor for driving the basket, said motor having a shaft,

a lug turning with the shaft, and means to open and close said cover comprising a collar surrounding the motor shaft, sa1d collar having a non-rotatable art en aging "said lug as the cover is moved towar open posiion.

13. In a protecting device for centrifugal machines, a counter-weighted cover, a handle for opening and closing said cover, .'a shaft rotatable to drive the machine, a pulby on the shaft having a flexible belt connection with the rotating element of the machine, the pulley having an abutment element, and a non-rotating part movable by the handle into the path of said abutment element as the cover is moved toward open position.

14. In a protecting device for centrifugal machines, a hinged cover for the machine,

no I

I raise and lower said cover, andmeans conmotor having a shaft straining said lever to move in a predetermined path whereby first to open said switch then to raise said cover and then to lock said cover in open position.

15. In a centrifuge, having a rotating element, a casing for housing the rotating element, a cover therefor, a motor connected to drive the rotating element, a switch there for, and a handle movable through a predetermined path first, to open sa1d switch, then after the motor has stopped, to open the cover to permit access to the inside of said casing.

16. In a centrifu e having a rotating element, a casing for fiousing the rotating element, a cover for the casing, a motor connected to drive the rotating element, said a switch for control- ;ling the motor, an abutment turning with the motor shaft, a non-rotatable stop normall out of the path of said abutment, a ban e, and guide means defining a substantiall han 1e bein movable along said path first to open said switch, then to move the stop element into the path of said abutment and simultaneously to open said cover whereby to insure stopping of the motor shaft before the cover is opened.

17. In a centrifu e, having a rotating element, a casing for ousing the rotating element, a counterweighted cover for the easing, an electric motor connected to drive the rotating element, said motor having a shaft,

U-shaped path for said handle, thea switch therefor, a toothed ring secured to the motor shaft, a non-rotatable toothed collar engageable with said toothed ring normally out of contact with the latter, a control lever, a guide providin a substan-. tially U-shaped path for the lever, means connecting the lever with the cover, the switch and thetoothed collar, the lever being movable along said path and acting first to open the switch, then simultaneously to open said cover and bring said collar into engagement with said toothed flange and then to lock said cover in open position whereby the cover can only be opened when the power is cut off and the-motor stopped.

18. In a protecting device for centrifugal machines, a cover for the machine, driving means for the machine, and means for operating the cover so arranged that the cover can be moved only when the driving means are stationary, but the machine may be rotated with the cover in either full open or full closed position.

19. In a protecting device for centrifugal machines, a cover for-the machine, driving means for the machine, and means for operating the cover so arranged that the cover can be moved only when the driving means are stationary, but the machine may be rotated by power only when the cover is in fully closed position and by hand when the cover is in fully open position.

Signed by me at Boston, Massachusetts this twenty-sixth da of March 1926.

CLARE CE H. GARLAND.

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